Magnesium alloy



Patented Mar. 27, 1951 MAGNESIUM ALLOY 7 Donald L. Leman, Freeland, and John J. Casey,

Midland, Mich, assignors to The Dow Chemical Company, Midland, Mich, a corporation of Delaware No Drawing. Application March 18, 1949, Serial No. 82,272

2 Claims.

The subject matter of this patent may be used by or for the Government for governmental purposes without the payment of any royalties.

The invention relates to magnesium base alloys. It more particularly concerns an improved quaternary magnesium base alloy containing lithium, zinc, and cadmium and exhibiting a high yield strength especially under compression loads.

The invention is based upon the discovery that by alloying together 6 to 12 per cent of lithium, 16 to 25 per cent of zinc, and 1 to 20 per cent of cadmium, the balance being essentially magnesium, a unique alloy results which exhibits excentionally high strength values and other useful properties. These properties render the alloy suitable for many structural uses in the arts. Preferred proportions in which to alloy the aforesaid metals are: lithium 7 to 10 per cent, zinc 16 to 20 per cent, cadmium 10 to 20 per cent, the balance being magnesium.

The following tabulated data are illustrative of the compression yield strength (defined as the load at which the stress strain curve deviates 0.2 per cent from the modulus line) of some representative examples of the alloy.

Table Nominal Composition in Per Cent by weight, 3511- 533 ance Ma nesium Strength in Lbs/Sq. In. Cd

sium, using about one part of flux for 10 parts of metal for protection from atmospheric attack. After the magnesium has melted the zinc and cadmium are added preferably at a temperature of about 1300" to 1400 F. Thereafter the lithium is added while the temperature of the melt is about 1250" F. To prevent the lithium from floating during alloying, it may be held in the molten metal by an inverted ladle.

After preparing a batch of each of the various compositions indicated, portions of the melt were cast into cylindrical ingots in a metal mold. After casting, the ingots were scalped and extruded hot (450 F.) from a 3 inch insidediameter container into strip x A" at the rate of 5 feet per minute and the extruded strip was cut into test specimens. Before making the compression strength tests, average values of which appear in the table, the specimens were subjected to a heat treatment by heating the specimens at 700 F. for 30 minutes, followed by quenching in Water at room temperature (except the last composition in the table which was quenched in oil).

' We claim: I

l. A magnesium base alloy composed of 6 to 12 per cent of lithium, 16 to 25 per cent of zinc, 1 to 20 per cent of cadmium, the balance being essentially magnesium.

2. A magnesium base alloy composed of '7 to 10 per cent of lithium, 16 to 20 per cent of zinc, 10 to 20 per cent of cadmium, the balance being magnesium.

DONALD L. LEMAN. JOHN J. CASEY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,910,431 Gann et a1 May 23, 1933 2,231,881 Burkhardt et al. Feb. 18, 1941 2,317,980 Dean et al. May 4, 1943 2,453,444 Loonam Nov. 9, 1948 GTHER REFERENCES Serial No. 303,611, Burkhardt et al. (A. P. 0.), pub. May 4, 1943, now abandoned.

Hume-Rothery et al., treatise in Journal Institute of Metals, vol. 71, 1945, page 601 (complete article pages 589-601, inclusive). 

1. A MAGNESIUM BASE ALLOY COMPOSED OF 6 TO 12 PER CENT OF LITHIUM, 16 TO 25 PER CENT OF ZINC, 1 TO 20 PER CENT OF CADMIUM, THE BALANCE BEING ESSENTIALLY MAGNESIUM. 